Abstract：
OBJECTIVE: To describe the in vivo emergence of ceftazidime-avibactam resistance in GES-type carbapenemases and to characterize an unusual outbreak of GES-6-producing Serratia marcescens during the COVID-19 pandemic in Spain.
METHODS: Retrospective study to describe a GES-CPSM outbreak based on whole genome sequencing and antimicrobial susceptibility testing (AST). Transferability of blaGES-carrying plasmid was assessed by conjugation experiments.
RESULTS: In December 2020, we identified a cluster of S. marcescens harbouring blaGES-6 involving 9 patients. Whole-genome sequence analysis revealed a clonal relationship (≤3 SNPs) between the first isolates identified in each of the evolved patients and environmental samples with GES-CPSM detection. Plasmid analysis showed that the blaGES-6 gene was located in an IncQ3-type plasmid. Triparental mating experiments using a helper plasmid demonstrated mobilization of the blaGES-6-carrying plasmid. Our results also demonstrate within-host evolution in S. marcescens isolates, leading to a transition from blaGES-6 to the new blaGES-55, caused by the P162S mutation, in a subsequent infection in one of the affected patients. In blaGES-55 we identified emergence of ceftazidime-avibactam resistance along with an increase of carbapenems susceptibility. This patient had been treated with a 14-day course of ceftazidime-avibactam. AST of the transformants bearing blaGES-6 and blaGES-55 plasmids, confirmed susceptibility variation affecting ceftazidime-avibactam and carbapenems.
CONCLUSIONS: We report an unusual outbreak of GES-6 whose incidence is becoming increasing. Transition from GES-6 to GES-55 may readily occur in vivo leading to ceftazidime-avibactam resistance, which brings to the fore the critical need for developing more accurate diagnosis tools for detection of GES β-lactamases and optimise the use of antimicrobials.
METHODS: Retrospective study to describe a GES-CPSM outbreak based on whole genome sequencing and antimicrobial susceptibility testing (AST). Transferability of blaGES-carrying plasmid was assessed by conjugation experiments.
RESULTS: In December 2020, we identified a cluster of S. marcescens harbouring blaGES-6 involving 9 patients. Whole-genome sequence analysis revealed a clonal relationship (≤3 SNPs) between the first isolates identified in each of the evolved patients and environmental samples with GES-CPSM detection. Plasmid analysis showed that the blaGES-6 gene was located in an IncQ3-type plasmid. Triparental mating experiments using a helper plasmid demonstrated mobilization of the blaGES-6-carrying plasmid. Our results also demonstrate within-host evolution in S. marcescens isolates, leading to a transition from blaGES-6 to the new blaGES-55, caused by the P162S mutation, in a subsequent infection in one of the affected patients. In blaGES-55 we identified emergence of ceftazidime-avibactam resistance along with an increase of carbapenems susceptibility. This patient had been treated with a 14-day course of ceftazidime-avibactam. AST of the transformants bearing blaGES-6 and blaGES-55 plasmids, confirmed susceptibility variation affecting ceftazidime-avibactam and carbapenems.
CONCLUSIONS: We report an unusual outbreak of GES-6 whose incidence is becoming increasing. Transition from GES-6 to GES-55 may readily occur in vivo leading to ceftazidime-avibactam resistance, which brings to the fore the critical need for developing more accurate diagnosis tools for detection of GES β-lactamases and optimise the use of antimicrobials.
摘要：
目的：描述GES型碳青霉烯酶体内头孢他啶-阿维巴坦耐药性的出现，并描述在西班牙COVID-19大流行期间产生GES-6的粘质沙雷菌的异常爆发。
方法：回顾性研究描述了基于全基因组测序和抗菌药物敏感性测试（AST）的GES-CPSM爆发。通过接合实验评估携带blaGES的质粒的可转移性。
结果：在2020年12月，我们确定了一组含有blaGES-6的粘质链球菌，涉及9例患者。全基因组序列分析显示，在每个进化患者中鉴定的第一批分离株与GES-CPSM检测的环境样品之间存在克隆关系（≤3个SNP）。质粒分析表明blaGES-6基因位于IncQ3型质粒中。使用辅助质粒的三亲本交配实验证明了携带blaGES-6的质粒的动员。我们的结果还证明了粘质沙氏菌分离株的宿主内进化，导致由P162S突变引起的从blaGES-6到新blaGES-55的转变，随后感染了一名受影响的患者。在blaGES-55中，我们发现了头孢他啶-阿维巴坦耐药性的出现以及碳青霉烯类抗生素敏感性的增加。该患者接受了14天的头孢他啶-阿维巴坦疗程。携带blaGES-6和blaGES-55质粒的转化体的AST，确认影响头孢他啶-阿维巴坦和碳青霉烯类的敏感性变化。
结论：我们报告了一次罕见的GES-6暴发，其发病率正在增加。从GES-6到GES-55的转变可能容易在体内发生，导致头孢他啶-阿维巴坦耐药性。这使人们迫切需要开发更准确的诊断工具来检测GESβ-内酰胺酶并优化抗微生物剂的使用。
方法：回顾性研究描述了基于全基因组测序和抗菌药物敏感性测试（AST）的GES-CPSM爆发。通过接合实验评估携带blaGES的质粒的可转移性。
结果：在2020年12月，我们确定了一组含有blaGES-6的粘质链球菌，涉及9例患者。全基因组序列分析显示，在每个进化患者中鉴定的第一批分离株与GES-CPSM检测的环境样品之间存在克隆关系（≤3个SNP）。质粒分析表明blaGES-6基因位于IncQ3型质粒中。使用辅助质粒的三亲本交配实验证明了携带blaGES-6的质粒的动员。我们的结果还证明了粘质沙氏菌分离株的宿主内进化，导致由P162S突变引起的从blaGES-6到新blaGES-55的转变，随后感染了一名受影响的患者。在blaGES-55中，我们发现了头孢他啶-阿维巴坦耐药性的出现以及碳青霉烯类抗生素敏感性的增加。该患者接受了14天的头孢他啶-阿维巴坦疗程。携带blaGES-6和blaGES-55质粒的转化体的AST，确认影响头孢他啶-阿维巴坦和碳青霉烯类的敏感性变化。
结论：我们报告了一次罕见的GES-6暴发，其发病率正在增加。从GES-6到GES-55的转变可能容易在体内发生，导致头孢他啶-阿维巴坦耐药性。这使人们迫切需要开发更准确的诊断工具来检测GESβ-内酰胺酶并优化抗微生物剂的使用。
